This invention relates to dispersing and removing solid wax-containing material from surfaces. More particularly, the invention relates to a process for removing solid wax-containing material from surfaces such as pipeline walls, well tubing flowlines, storage vessels, and similar equipment.
Petroleum fluids produced from wells frequently contain wax which deposits in the wellbore and in equipment utilized for producing and transporting the petroleum fluids. Also, the wax tends to accumulate in pipelines, storage vessels, and other equipment wherein the petroleum fluids are processed. This is a serious problem in that the deposition of wax interferes with the production, transportation, storage, and processing of the petroleum fluids containing such wax. Wax deposition may proceed to the point where production is completely interrupted or flowline flow is stopped. The problem of removing wax deposits from pumping wells and flowlines has been attacked in a number of ways. Perhaps the most effective and oldest method heretofore, was to clean the well or flowline mechanically, e.g., by scraping, which resulted in lost production time and high labor costs and required special tools, all of which was often too expensive to be economically feasible.
Another common practice to try to restore the flow of a well or flowline is by cleaning the well or flowline with chemical solvents. Hot oil or solvent has been introduced in the well or flowline in an effort to dissolve the wax. However, the solvents used in the prior art, have been effective only to dissolve the wax and other hydrocarbons that are readily soluble in organic media. Also, the use of such solvents has been a time consuming and costly operation and has resulted in considerable loss of production time. Thus, the prior art method of cleaning wells by the use of solvents, has been largely ineffective and in many instances has served only to worsen the fouling of the flowlines or well by redeposition as the hot solvent cooled.
Another technique to remove wax deposits from wells and flowlines resides in utilizing an acid-base reaction to generate heat in situ in order to dissolve the deposited wax. Such cleaning operations however, have been less than satisfactory for one reason or another. Thus, it has been difficult to control the heat of reaction necessary to provide the desired high temperature needed for efficient wax removal, without redeposition of the wax and/or damage to the equipment.
Applicant is not aware of any prior art which, in his judgment as one skilled in the pipeline art, would anticipate or render obvious the novel method of the present invention; however, for the purposes of fully developing the background of the invention and establishing the state of the requisite art, the following is set forth: U.S. Pat. Nos. 4,089,703; 4,174,271; 4,442,014.